Balalaiev O.K, Bezruchko K.А., Burchak O.V., Pymonenko L.I., Baranovskyi V.H., Serikov Yu.А. Analytical review of electrical phenomena research in coalification in view of the scale hierarchy

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Parent Category: Geo-Technical Mechanics, 2023

Category: Geo-Technical Mechanics, 2023, Issue 166

Geoteh. meh. 2023, 166, 5-14

https://doi.org/10.15407/geotm2023.166.005 

 

ANALYTICAL REVIEW OF ELECTRICAL PHENOMENA RESEARCHIN COALIFICATION IN VIEW OF THE SCALE HIERARCHY

Balalaiev O.K, Bezruchko K.А., Burchak O.V., Pymonenko L.I., Baranovskyi V.H., Serikov Yu.А.

M.S. Poliakov Institute of Geotechnical Mechanics of the National Academy of Sciences of Ukraine

UDC 553.9:544.5:620.1

Language: English

Abstract. Electrical processes in carboniferous rocks saturated with organic matter have to be considered at three scale levels: the macrolevel of the bed, the mesolevel of the sample, and the microlevel of the point. The electrical resistivity of coal is affected by rank, humidity, salinity, temperature, and other parameters. Temperature changes in the electrical conductivity of coals strongly depend on the thermal history of the bed and have a complex multi-stage nature as the sample heats up, due to multidirectional processes. Thermal activation of coals leads to an increase in the number of charge carriers in a local continuous microregion. At the same time, the process of hollow crack formation prevents the growth of electrical conductivity on a macroscale. During underground fires of coal beds, the electrical resistivity decreases significantly at the source of the fire, and an abnormally high value of electrical self-potential is recorded on the surface of the earth. The specific electrical conductivity of a moisture-saturated coal bed can increase significantly due to the ionic conductivity of pore electrolytic solutions. The dielectric properties of coals are highly dependent on rank, temperature, and humidity. The relative dielectric constant increases with increasing temperature. The ultra-high-frequency broadband spectrum has a complex shape with many local maxima. Dielectric losses tend to rise with increasing frequency and differ significantly for coals of different ranks. Coals subjected to uniaxial compression and shear loading can produce ultra-low-frequency electromagnetic radiation signals that correlate well with applied stress and acoustic emission. The physical nature of the electromagnetic emission of a coal bed, caused by the movement of charges on the surface of pores and cracks, can be explained by the large-scale effect of the microsurface self-potential of coal. Metamorphism can affect the surface potential of coals through the evolution of polar functional groups, distribution of surface microstructures, micromorphology, internal connectivity, and heterogeneity. The purpose of the work is to review, analyze, and systematize published experimental research on the electrical properties of coals depending on the metastable structure of their carbon matrix and external factors at different scale levels.
Keywords: coal, scale hierarchy, electrical conductivity, dielectric constant, self-potential, electromagnetic emission.

 

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About the authors:

Balalaiev Oleksandr Kostiantynovych, Candidate of Biology Sciences (Ph.D.), Senior Researcher, Senior Researcher in Department of Geology of Coal Beds at Great Depths, M.S. Poliakov Institute of Geotechnical Mechanicsof the National Academy of Sciences of Ukraine (IGTM of the NAS of Ukraine), Dnipro, Ukraine, This email address is being protected from spambots. You need JavaScript enabled to view it.

Bezruchko Kostiantyn Andriovych, Doctor of Geology Science (D.Sc.), Senior Researcher, Head of Department of Geology of Coal Beds at Great Depths, M.S. Poliakov Institute of Geotechnical Mechanicsof the National Academy of Sciences of Ukraine (IGTM of the NAS of Ukraine), Dnipro, Ukraine, This email address is being protected from spambots. You need JavaScript enabled to view it.

Burchak Oleksandr Vasylovych, Doctor of Technic Science (D.Sc.), Senior Researcher, Senior Research in Department of Geology of Coal Beds at Great Depths, M.S. Poliakov Institute of Geotechnical Mechanicsof the National Academy of Sciences of Ukraine (IGTM of the NAS of Ukraine), Dnipro, Ukraine, This email address is being protected from spambots. You need JavaScript enabled to view it.

Pymonenko Liudmyla Ivanivna, Doctor of Geology Science (D.Sc.), Senior Researcher, Principal Researcher in the Department of Geology of Coal Beds at Great Depths, M.S. Poliakov Institute of Geotechnical Mechanics of the National Academy of Sciences of Ukraine (IGTM of the NAS of Ukraine), Dnipro, Ukraine, This email address is being protected from spambots. You need JavaScript enabled to view it.

Baranovskyi Volodymyr Hnatovych, Junior Researcher in the Department of Geology of Coal Beds at Great Depths, M.S. Poliakov Institute of Geotechnical Mechanics of the National Academy of Sciences of Ukraine (IGTM of the NAS of Ukraine), Dnipro, Ukraine, This email address is being protected from spambots. You need JavaScript enabled to view it.

Serikov Yurii Anatoliyovych, Engineer in the Department of Geology of Coal Beds at Great Depths, M.S. Poliakov Institute of Geotechnical Mechanics under the National Academy of Sciences of Ukraine (IGTM of the NAS of Ukraine), Dnipro, Ukraine

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